A multi-stage coaxial speed reducer

Abstract

This invention relates to the field of speed reducer technology, specifically to a multi-stage coaxial speed reducer, comprising an outer cylinder containing a first-stage gear ring and second / third-stage gear rings, and a first-stage, second-stage, and third-stage speed reducer arranged sequentially within the outer cylinder. The first-stage planetary carrier skeleton is axially fixed, while the second and third-stage planetary carrier skeletons are axially floating. Interstage washers / thrust bearings provide axial support and friction reduction, and the final third-stage planetary gears employ staggered gears to eliminate meshing backlash. This invention achieves a balance between a large reduction ratio and a compact structure through a coaxial compact integrated design; interstage friction-reducing support and an adaptive speed lubrication circulation design significantly reduce friction loss and improve transmission efficiency; staggered backlash elimination, elastic buffering, and a stable shaft system effectively reduce gear wear and impact loads, significantly extending service life. It also boasts advantages such as high transmission accuracy, fast response, and stable operation, making it suitable for applications such as precision transmissions and automotive active stabilizer bars.

Description

Technical Field

[0001] This invention relates to the field of speed reducer technology, and specifically to a multi-stage coaxial speed reducer. Background Technology

[0002] Planetary gear reducers are widely used in high-end equipment and automotive parts fields such as industrial robots, precision machine tools, servo transmission systems, new energy vehicles, automated production lines, and automotive chassis stabilizer bar actuators. They are core components for achieving power reduction and torque amplification, and precise motion transmission. As modern equipment develops towards miniaturization, integration, and heavy-duty operation, higher demands are placed on reducer performance. They not only need large reduction ratios to meet low-speed, high-torque output requirements, but also compact structures to fit limited installation space. However, existing reducer technologies generally suffer from the inability to simultaneously achieve both large reduction ratios and compact structures. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a multi-stage coaxial reducer that balances a large reduction ratio with a compact structure.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] On the one hand, a multi-stage coaxial reducer is provided, including an outer cylinder, in which a first-stage gear ring and a second / third-stage gear ring are disposed, and a first-stage reducer, a second-stage reducer and a third-stage reducer are disposed in sequence and coaxially arranged in the outer cylinder;

[0006] The first-stage reducer includes a first-stage planetary carrier frame, which is fixed in an axial position. Several first-stage planetary cavities are reserved inside the first-stage planetary carrier frame. First-stage planetary gears are rotatably connected inside the first-stage planetary cavities, and all first-stage planetary gears mesh with the first-stage ring gear. A second-stage sun gear is coaxially fixedly connected to the first-stage planetary carrier frame.

[0007] The secondary reducer includes a secondary planetary carrier frame, which floats axially. Several secondary planetary cavities are pre-reserved within the secondary planetary carrier frame, and secondary planetary gears are rotatably connected within these cavities. Each secondary planetary gear meshes with the secondary sun gear and the second / third stage ring gear. A third stage sun gear is coaxially and fixedly connected to the secondary planetary carrier frame.

[0008] The three-stage reducer includes a three-stage planetary carrier frame, which floats axially. Several three-stage planetary cavities are reserved inside the three-stage planetary carrier frame. Three-stage planetary gears are rotatably connected inside the three-stage planetary cavities. All three-stage planetary gears mesh with the three-stage sun gear and the second / third-stage ring gear. The three-stage planetary carrier frame is connected to an output mechanism.

[0009] The above scheme constructs a compact multi-stage coaxial planetary reducer, and the multi-stage series reducer structure has a large reduction ratio.

[0010] Furthermore, a first washer is provided between the secondary planetary carrier frame and the tertiary planetary carrier frame, and the first washer between the two is in contact with or abuts against the secondary planetary carrier frame; a second washer is provided between the primary planetary carrier frame and the secondary planetary carrier frame, and the second washer between the two is in contact with or abuts against the primary planetary carrier frame; the first washer, the second washer, the secondary sun gear, and the tertiary sun gear are coaxial.

[0011] Furthermore, a first thrust bearing is provided between the secondary planetary carrier frame and the tertiary planetary carrier frame, and the first thrust bearing between them contacts and abuts against the secondary planetary carrier frame or the tertiary planetary carrier frame; a second thrust bearing is provided between the primary planetary carrier frame and the secondary planetary carrier frame, and the second thrust bearing between them contacts and abuts against the primary planetary carrier frame or the secondary planetary carrier frame; the first thrust bearing, the second thrust bearing, the secondary sun gear, and the tertiary sun gear are coaxial.

[0012] The above solution provides lubrication and support between the planetary carrier frames by setting a first washer and a second washer / first thrust bearing and a second thrust bearing, reducing clearance, improving operational stability, and reducing contact area and heat generation; at the same time, it reduces efficiency loss caused by rotational rolling friction between the planetary carrier frames and improves transmission efficiency.

[0013] Furthermore, a third washer is provided on the inner top wall of the third-stage planetary carrier frame, and a T-shaped washer is coaxially inserted into the third-stage sun gear. The T-shaped washer is made of elastic material, extends to the outside of the third-stage sun gear, and covers the end face of the third-stage sun gear. The T-shaped washer is located between the third washer and the end face of the third-stage sun gear.

[0014] The above solution uses a T-shaped washer to prevent the third washer from directly contacting the end face of the third-stage sun gear, thus reducing wear on the third-stage sun gear. At the same time, since the T-shaped washer is made of elastic material, it can absorb the impact generated by the third-stage planetary carrier frame. Furthermore, it reduces the efficiency loss caused by the rotational rolling friction between the third-stage planetary carrier frame and the third-stage sun gear, thereby improving the transmission efficiency.

[0015] Furthermore, the output mechanism includes a petal-shaped boss fixedly connected to the three-stage planetary carrier skeleton, an output bearing is provided inside the outer cylinder, an output sleeve is rotatably connected inside the outer cylinder through the output bearing, a petal-shaped groove is provided inside the output sleeve, the petal-shaped boss is inserted into the petal-shaped groove, and an elastic layer is provided between the petal-shaped boss and the petal-shaped groove, and the output sleeve is used to connect the output end.

[0016] The above solution stabilizes the power output of the three-stage reducer through the petal-shaped boss and the petal-shaped groove. The elastic layer between the petal-shaped boss and the petal-shaped groove reduces the impact vibration of each stage of the reducer and reduces the transmission of impact vibration from the output end to the reducer.

[0017] Furthermore, the outer cylinder is provided with a bearing mounting groove, and the inner wall of the bearing mounting groove on the side away from the third-stage planetary carrier skeleton is provided with an external thread. A fixed outer ring is fixedly connected to the outer cylinder through the external thread, and the fixed outer ring fixes the outer ring of the output bearing to the bearing mounting groove. The output sleeve is provided with an annular boss on the side near the third-stage planetary carrier skeleton, and the outer wall of the output sleeve on the side away from the third-stage planetary carrier skeleton is provided with an internal thread. A fixed inner ring is fixedly connected to the outside of the output sleeve through the internal thread, and the fixed inner ring fixes the inner ring of the output bearing between the fixed inner ring and the annular boss.

[0018] The above solution uses internal / external threaded connections to fix the bearing, achieving a stable fixation of the output bearing position and facilitating assembly.

[0019] Furthermore, the primary gear ring is press-fitted or welded to the inner wall of the outer cylinder, and the secondary / tertiary gear rings are integrally formed on the inner wall of the outer cylinder. The secondary / tertiary gear rings consist of an installation section and a meshing section with different tooth tip diameters and the same tooth root diameter. The tooth tips between the installation section and the meshing section are smoothly transitioned by a chamfer. The tooth tip diameter of the meshing section is smaller than that of the installation section, and the meshing section is located on the side closer to the primary gear ring.

[0020] The above solution, by setting second / third stage gear rings of different diameters, facilitates the press-fitting of staggered gears, thereby improving the convenience and stability of assembly.

[0021] Furthermore, a primary protrusion is provided at one end of the primary planetary carrier skeleton near the secondary planetary carrier skeleton, and the secondary sun gear is fixedly connected to the primary protrusion. A secondary protrusion is provided at one end of the secondary planetary carrier skeleton near the tertiary planetary carrier skeleton, and the tertiary sun gear is fixedly connected to the end face of the secondary protrusion. The secondary sun gear does not contact the secondary protrusion.

[0022] In the above scheme, the fixing method between the secondary sun gear and the primary protrusion, as well as between the tertiary sun gear and the secondary protrusion, can be welding or spline connection. The protrusion structure avoids wear between the planetary carrier skeleton and the sun gear, and reduces the heat generation inside the reducer.

[0023] Furthermore, at least one of the three-stage planetary gears is a staggered gear; the staggered gear includes at least two sub-gears, each sub-gear having a limiting portion constructed thereon, each sub-gear being sleeved on the three-stage planetary shaft, the three-stage planetary shaft being disposed in the three-stage planetary cavity, and an elastic preload member being disposed between adjacent sub-gears, the two ends of the elastic preload member respectively contacting and abutting against the limiting portion of the adjacent sub-gear, providing preload forces in opposite directions to the adjacent sub-gears, so that a misalignment angle is formed between the opposing teeth of the adjacent sub-gears.

[0024] The above solution eliminates the meshing gap between the third-stage planetary gear and the second / third-stage gear ring by setting staggered gears in the three-stage reducer. This allows for rapid response during forward and reverse operation of the reducer, reduces response delay caused by meshing gap, and improves transmission accuracy.

[0025] Furthermore, the third-stage planetary cavity sidewall has a first fixing hole, and the third-stage planetary shaft sidewall has a second fixing hole. The first fixing hole and the second fixing hole are fitted with elastic cylindrical pins, and the elastic cylindrical pins provide radial force to the sidewalls of the first fixing hole and the second fixing hole.

[0026] The above solution achieves a stable fixation of the planetary shaft through elastic cylindrical pins, and can still maintain a good fixation effect under impact and vibration conditions.

[0027] Beneficial effects:

[0028] This invention provides a multi-stage coaxial reducer that balances a large reduction ratio with a compact structure through improved design between the multiple stages. By incorporating staggered gears in the three-stage reducer and utilizing the offset angle to eliminate tooth backlash, it solves the problem of lag response in existing reducers, improving transmission accuracy and response speed. Simultaneously, the use of washers and thrust bearings improves lubrication, reduces heat generation and wear, and enhances overall operational stability. Furthermore, the output mechanism employs an elastic layer connection, effectively buffering impact vibrations and improving NVH performance. Attached Figure Description

[0029] Figure 1 This is an isometric view of the reducer according to an embodiment of the present invention;

[0030] Figure 2 This is a front view of the overall reducer according to an embodiment of the present invention;

[0031] Figure 3 for Figure 2 AA section view;

[0032] Figure 4 This is an exploded view of the output mechanism according to an embodiment of the present invention;

[0033] Figure 5 This is an exploded view of the deceleration mechanism according to an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of the outer cylinder explosion according to an embodiment of the present invention;

[0035] Figure 7 This is a front view of the deceleration mechanism in its assembled state according to an embodiment of the present invention;

[0036] Figure 8 This is a cross-sectional view of the deceleration mechanism in its assembled state according to an embodiment of the present invention;

[0037] Figure 9 This is a schematic diagram of the assembly state of the output sleeve and output bearing according to an embodiment of the present invention;

[0038] Figure 10 This is a cross-sectional view of the output sleeve and output bearing in an assembly state according to an embodiment of the present invention;

[0039] Figure 11 This is a cross-sectional view of the outer cylinder in its assembled state according to an embodiment of the present invention;

[0040] Figure 12 This is an isometric view of the deceleration mechanism according to an embodiment of the present invention;

[0041] Figure 13 This is an exploded view of the deceleration mechanism according to an embodiment of the present invention;

[0042] Figure 14 This is a front view of the deceleration mechanism according to an embodiment of the present invention;

[0043] Figure 15 for Figure 14 CC section view;

[0044] Figure 16 This is an isometric view of the deceleration mechanism in Embodiment 5 of the present invention;

[0045] Figure 17 This is an exploded schematic diagram of the deceleration mechanism in Embodiment 5 of the present invention;

[0046] Figure 18 This is a front view of the deceleration mechanism in Embodiment 5 of the present invention;

[0047] Figure 19 for Figure 18 BB cross-sectional view;

[0048] Figure 20These are isometric views of the reduction mechanism in embodiments 7 and 8 of the present invention;

[0049] Figure 21 This is an exploded schematic diagram of the deceleration mechanism in embodiments 7 and 8 of the present invention.

[0050] The reference numerals in the accompanying drawings include:

[0051] 01. Fixed terminal; 02. Output terminal;

[0052] 11. Outer cylinder; 12. First-stage gear ring; 13. Input shaft; 14. First floating disc; 15. Second floating disc; 16. First recess; 17. Second recess; 18. First through hole; 19. Second through hole; 20. First thrust bearing; 21. Third-stage planetary shaft; 22. First fixing hole; 23. Second fixing hole; 24. Elastic cylindrical pin;

[0053] 100. Output mechanism; 101. Output bearing; 102. Output sleeve; 103. Fixed inner ring; 104. Fixed outer ring; 105. Petal-shaped boss; 106. Petal-shaped groove;

[0054] 200. Reduction mechanism; 201. Single-stage reducer; 202. Two-stage reducer; 203. Three-stage reducer;

[0055] 2011, Primary planetary carrier frame; 2012, Primary planetary gears; 2013, Secondary sun gear; 2014, Primary protrusion;

[0056] 2021, Second-stage planetary carrier framework; 2022, Second-stage planetary gears; 2023, Third-stage sun gear; 2024, Second-stage protrusion;

[0057] 2031, Third-stage planetary support framework; 2032, Third-stage planetary gears;

[0058] 301. Second washer; 302. Third washer; 303. Elastic layer; 304. Sub-gear; 305. Elastic preload; 306. Alternating gear. Detailed Implementation

[0059] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0061] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0062] The following detailed description illustrates the specific implementation method:

[0063] Example 1: As Figures 1 to 3 and Figure 5 As shown, this embodiment provides a multi-stage coaxial reducer. The multi-stage coaxial reducer includes an outer cylinder 11, a first-stage gear ring 12 disposed inside the outer cylinder 11, a second / third-stage gear ring disposed on the inner wall of the outer cylinder 11, and a reduction mechanism 200 disposed inside the outer cylinder 11. The reduction mechanism 200 consists of a first-stage reducer 201, a second-stage reducer 202, and a third-stage reducer 203 arranged coaxially in sequence.

[0064] Specifically, the outer cylinder 11 serves as the main housing of the reducer, providing a mounting base and protection for the internal reduction components. The primary gear ring 12 is fixedly installed inside the outer cylinder 11, for example, by interference fit press fitting or by welding. The secondary / tertiary gear rings are integrally formed on the inner wall of the outer cylinder 11, for example, by broaching. The primary reducer 201, secondary reducer 202, and tertiary reducer 203 are arranged coaxially in series along the axial direction to achieve progressive power reduction and torque increase transmission.

[0065] The first-stage reducer 201 includes a first-stage planetary carrier frame 2011, which has several first-stage planetary cavities. First-stage planetary gears 2012 are rotatably connected in the first-stage planetary cavities, and all first-stage planetary gears 2012 mesh with the first-stage gear ring 12. A second-stage sun gear 2013 is fixedly connected to the outside of the first-stage planetary carrier frame 2011.

[0066] In this embodiment, an input shaft 13 is also provided inside the outer cylinder 11. The input shaft 13 is coaxially integrated with the output shaft of the drive element (usually a motor). The input shaft 13 serves as the sun gear of the first-stage reducer 201 and meshes with each of the first-stage planetary gears 2012. When the input shaft 13 is rotated by the power of the external drive element, it drives the first-stage planetary gears 2012 to rotate. The first-stage planetary gears 2012 revolve under the constraint of the first-stage ring gear 12, thereby driving the first-stage planetary carrier frame 2011 to rotate. Finally, the first-stage planetary carrier frame 2011 drives the second-stage sun gear 2013 to rotate synchronously, realizing the first-stage reduction output. In this embodiment, the first-stage ring gear 12, the first-stage planetary gears 2012, and the input shaft 13 are all helical gears. Helical gear meshing generates less noise during operation. However, due to the high difficulty and cost of machining helical gears, the first-stage ring gear 12 in this embodiment is externally machined and then assembled into the outer cylinder 11.

[0067] The two-stage reducer 202 includes a two-stage planetary carrier frame 2021, which has several two-stage planetary cavities. Two-stage planetary gears 2022 are rotatably connected in the two-stage planetary cavities. The two-stage planetary gears 2022 mesh with the two-stage sun gear 2013 and the two / three-stage ring gear. A three-stage sun gear 2023 is fixedly connected to the outside of the two-stage planetary carrier frame 2021.

[0068] In this structure, the second-stage sun gear 2013 serves as the sun gear of the second-stage reducer 202. The second-stage sun gear 2013 transmits the power from the first-stage reduction to the second-stage planetary gear 2022. The second-stage planetary gear 2022 simultaneously meshes with both the second-stage sun gear 2013 and the second / third-stage ring gear on the outer cylinder 11. While rotating on its own axis, the second-stage planetary gear 2022 revolves around the second / third-stage ring gear, driving the second-stage planetary carrier frame 2021 to rotate, which in turn drives the third-stage sun gear 2023 fixed to it to rotate, completing the second-stage reduction process.

[0069] The three-stage reducer 203 includes a three-stage planetary carrier frame 2031, which has several three-stage planetary cavities. Three-stage planetary gears 2032 are rotatably connected in the three-stage planetary cavities. All three-stage planetary gears 2032 mesh with the three-stage sun gear 2023 and the second / third stage ring gear. The three-stage planetary carrier frame 2031 is connected to an output mechanism 100.

[0070] like Figure 6 As shown, a fixed end 01 is fixedly connected to one end of the outer cylinder 11, and the overall housing of the reducer is fixed through the fixed end 01.

[0071] Similarly, the third-stage sun gear 2023, acting as the sun gear of the third-stage reducer 203, transmits power to the third-stage planetary gear 2032. The third-stage planetary gear 2032 meshes with the second / third-stage ring gear, driving the third-stage planetary carrier frame 2031 to rotate, and finally outputs torque outward through the output mechanism 100. In this embodiment, the second / third-stage ring gear, the second-stage planetary gear 2022, the third-stage planetary gear 2032, the second-stage sun gear 2013, and the third-stage sun gear 2023 are all spur gears. Using spur gears is convenient for processing and has a lower manufacturing cost. Therefore, in this embodiment, the second / third-stage ring gear is integrally formed on the inner wall of the outer cylinder 11.

[0072] In this embodiment, the primary gear ring 12, the primary planetary carrier skeleton 2011, and the input shaft 13 are fixed in axial position; specifically, combined with Figure 3 As shown, the first-stage planetary carrier skeleton 2011 near the input shaft 13 is fitted with a bearing, which limits the first-stage planetary carrier skeleton 2011 and fixes its position in the axial direction; the first-stage gear ring 12 is fixedly connected, and the input shaft 13 is fixedly connected to the output shaft of the drive element, so the first-stage gear ring 12 and the input shaft 13 are fixed in the axial direction.

[0073] The second / third stage gear ring and the second stage sun gear 2013 are fixed in the axial direction, while the second stage planetary carrier skeleton 2021 is floating in the axial direction; the third stage planetary carrier skeleton 2031 and the third stage sun gear 2023 are also floating in the axial direction. Specifically, since the second / third stage gear ring is integrally formed on the side wall of the outer cylinder 11, and the second stage sun gear 2013 is fixedly connected to the fixed first stage planetary carrier skeleton 2011, the second / third stage gear ring and the second stage sun gear 2013 are fixed in the axial direction; since the second stage planetary carrier skeleton 2021 and the second stage planetary gear 2022 are not fixedly constrained, they are floating in the axial direction; since the third stage sun gear 2023 is fixedly connected to the second stage planetary carrier skeleton 2021, and the third stage planetary carrier skeleton 2031 is not fixedly constrained, they are also floating in the axial direction.

[0074] The above structure evenly distributes the total load in the entire reducer, thereby increasing the service life of the gear meshing.

[0075] In this embodiment, at least one third-stage planetary gear 2032 is a staggered-tooth gear 306. Specifically, the staggered-tooth gear 306 serves as a gear structure capable of automatically eliminating backlash. In the three-stage reducer 203, the third-stage planetary gear 2032 is a key component of the final stage transmission link, and the meshing clearance between it and the second / third-stage ring gear directly determines the transmission accuracy and response speed of the reducer output end O2. If backlash exists, idle stroke will occur during forward / reverse switching or frequent start / stop conditions, resulting in response lag. In this embodiment, by setting at least one third-stage planetary gear 2032 as a staggered-tooth gear 306, the staggered-tooth gear 306 utilizes its own structural characteristics to automatically compensate for or eliminate the backlash between the third-stage planetary gear 2032 and the second / third-stage ring gear during meshing. This enables the reducer to achieve backlash-free meshing during forward / reverse operation, making power transmission more direct and sensitive, thereby significantly improving the dynamic response speed and transmission accuracy of the reducer. It is particularly suitable for applications with extremely high response speed requirements, such as active stabilizer bars in automobiles. It should be understood that the specific structural forms of the staggered gear 306 are diverse, as long as they can achieve the function of eliminating tooth backlash.

[0076] Example 2: This example optimizes the support and lubrication structure between the skeletons, based on Example 1. For example... Figure 5 and Figure 8 As shown, a primary planetary carrier frame 2011 has a primary protrusion 2014 near the end of the secondary planetary carrier frame 2021, and a secondary sun gear 2013 is fixedly connected to the primary protrusion 2014. A secondary planetary carrier frame 2021 has a secondary protrusion 2024 near the end of the tertiary planetary carrier frame 2031, and a tertiary sun gear 2023 is fixedly connected to the end face of the secondary protrusion 2024. The secondary sun gear 2013 does not contact the secondary protrusion 2024. In some embodiments, the secondary sun gear 2013 and the primary protrusion 2014 are fixedly welded together. In other embodiments, the secondary sun gear 2013 and the primary protrusion 2014 are connected by a spline connection, and the tertiary sun gear 2023 and the secondary protrusion 2024 are connected by a spline connection.

[0077] Specifically, the design of the primary protrusion 2014 and the secondary protrusion 2024 changes the traditional connection method where the output wheel is flush with the plane of the frame in a reducer. In this embodiment, the primary protrusion 2014 can be directly stamped from the primary planetary carrier frame 2011, forming a circular protrusion. The secondary sun gear 2013 is fixed to the end face of this protrusion, creating a gap between the back of the secondary sun gear 2013 and the main surface of the primary planetary carrier frame 2011. Similarly, the secondary protrusion 2024 supports the tertiary sun gear 2023. The core advantage of this structural design is that, as a high-speed rotating component, the back of the secondary sun gear 2013 no longer directly rubs against the secondary planetary carrier frame 2021. Instead, it is isolated by the primary protrusion 2014, and the secondary sun gear 2013 does not contact the secondary protrusion 2024. This effectively avoids wear on the secondary planetary carrier frame 2021 caused by the high-speed rotating secondary sun gear 2013, significantly reducing the heat generated inside the reducer.

[0078] Based on the above, such as Figure 5 As shown, some embodiments employ the following scheme to further optimize interstage support and lubrication:

[0079] A first washer (not shown in the attached diagram) is provided between the secondary planetary carrier 2021 and the tertiary planetary carrier 2031. In the non-operating state, the first washer contacts and abuts against either the secondary or tertiary planetary carrier 2021. In the operating state, due to the floating of the secondary planetary carrier 2021, the end face of the first washer may contact and abut against both the secondary and tertiary planetary carriers 2021. A second washer 301 is provided between the primary planetary carrier 2011 and the secondary planetary carrier 2021. In the non-operating state, the second washer 301 contacts and abuts against either the primary or secondary planetary carrier 2021. In the operating state, due to the floating of the secondary planetary carrier 2021, the end face of the second washer 301 may contact and abut against both the primary and secondary planetary carriers 2011.

[0080] The first and second washers 301 provide lubrication and support between the planetary carrier skeletons, reducing clearance, improving operational stability, and reducing contact area and heat generation; at the same time, they eliminate the efficiency loss caused by the rotational rolling friction between the planetary carrier skeletons, thus improving transmission efficiency.

[0081] refer to Figures 12 to 15 As shown, some other embodiments further optimize interstage support and lubrication using the following methods:

[0082] A first thrust bearing 20 is provided between the secondary planetary carrier 2021 and the tertiary planetary carrier 2031. In the non-operating state, the first thrust bearing 20 contacts and abuts against either the secondary or tertiary planetary carrier 2021. In the operating state, due to the floating of the secondary planetary carrier 2021, the shaft ring and seat ring of the first thrust bearing 20 may contact and abut against the secondary and tertiary planetary carriers 2021, respectively. A second thrust bearing (not shown in the attached diagram) is provided between the primary planetary carrier 2011 and the secondary planetary carrier 2021. In the non-operating state, the second thrust bearing contacts and abuts against either the primary or secondary planetary carrier 2011. In the operating state, the shaft ring and seat ring of the second thrust bearing may contact and abut against both the primary and secondary planetary carriers 2011, respectively.

[0083] The first thrust bearing 20 and the second thrust bearing provide lubrication and support between the planetary carrier skeletons, reducing clearance, improving operational stability, and reducing contact area and heat generation; at the same time, they eliminate the efficiency loss caused by the rotational rolling friction between the planetary carrier skeletons and improve transmission efficiency.

[0084] In addition, some embodiments have a third washer 302 provided on the inner top wall of the third-stage planetary carrier frame 2031, and a T-shaped washer (not shown in the figure) coaxially inserted into the third-stage sun gear 2023. The T-shaped washer is made of elastic material (preferably nylon 66 (PA66) material), extends to the outside of the third-stage sun gear 2023 and covers the end face of the third-stage sun gear 2023, and the T-shaped washer contacts and abuts against the third washer 302.

[0085] The T-shaped washer prevents direct contact between the third washer 302 and the end face of the third-stage sun gear 2023, reducing wear on the third-stage sun gear 2023. At the same time, since the T-shaped washer is made of elastic material, it can absorb the impact generated by the third-stage planetary carrier 2031. It also eliminates the efficiency loss caused by the rotational rolling friction between the third-stage planetary carrier 2031 and the third-stage sun gear 2023.

[0086] Similarly, the third washer 302 is installed inside the third-stage planetary carrier frame 2031. The third washer 302 contacts and abuts against the T-shaped washer, and is supported between the third-stage sun gear 2023 and the inner top wall of the third-stage planetary carrier frame 2031, providing stable axial support for the final stage transmission.

[0087] It should be understood that the materials of the first washer, the second washer 301 and the third washer 302 can be selected according to the actual working conditions, such as metal washers, wear-resistant plastic washers or composite material washers, as long as they can meet the requirements of support strength and wear resistance.

[0088] It is particularly important to emphasize that the first washer, the second washer 301, the second-stage sun gear 2013, and the third-stage sun gear 2023 are coaxial; the first thrust bearing 20, the second thrust bearing, the second-stage sun gear 2013, and the third-stage sun gear 2023 are also coaxial. This coaxial design ensures the geometric axis consistency of the power transmission path, avoiding additional radial forces and vibrations caused by eccentricity, thereby guaranteeing the transmission stability of the multi-stage reducer under high-speed operation. Through the cooperation of the raised structure and the washer structure, this embodiment constructs a complete technical unit for support, lubrication, and wear prevention, effectively solving the heat dissipation and stability problems of the multi-stage reducer in a compact space.

[0089] The first and second washers 301 / first thrust bearing 20 and second thrust bearing not only provide axial support and bear part of the axial force, but more importantly, their presence reduces the direct contact area between the two metal frames. During reducer operation, grease / oil can more easily accumulate in the micro-gap between the washers and the frame, forming a stable lubricating film, thereby further reducing frictional heat generation.

[0090] Example 3: This example further refines the specific structure of the output mechanism 100 based on Example 1. For example... Figure 4 , Figures 7 to 11 As shown, the output mechanism 100 includes a petal-shaped boss 105 fixedly connected to the three-stage planetary carrier frame 2031. An output bearing 101 (a double-row angular contact bearing) is provided inside the outer cylinder 11. An output sleeve 102 is rotatably connected inside the outer cylinder 11 through the output bearing 101. A petal-shaped groove 106 is provided inside the output sleeve 102. The petal-shaped boss 105 is embedded in the petal-shaped groove 106, and an elastic layer 303 is provided between the petal-shaped boss 105 and the petal-shaped groove 106. The output sleeve 102 is used to connect the output end 02.

[0091] Specifically, the three-stage planetary carrier 2031, as the final power output carrier, needs to transmit its rotation to the final output sleeve 102. This embodiment employs a petal-shaped boss 105 and a petal-shaped groove 106. This polygonal or involute spline-shaped mating structure can reliably transmit torque. More importantly, an elastic layer 303 is provided between the petal-shaped boss 105 and the petal-shaped groove 106. This elastic layer 303 is preferably vulcanized rubber, directly formed on the surface of the petal-shaped boss 105 or the inner wall of the petal-shaped groove 106 through a vulcanization process. When the three-stage planetary carrier 2031 drives the petal-shaped boss 105 to rotate, the torque is transmitted to the output sleeve 102 through the elastic layer 303. The presence of the elastic layer 303 is equivalent to introducing a flexible link in the transmission chain, which can effectively absorb and buffer the impact vibration generated by the meshing of gears inside the reducer, as well as the reverse impact of sudden changes in external load on the internal structure of the reducer. This has a significant effect on improving the NVH (noise, vibration, and harshness) performance of the whole vehicle, especially in scenarios where ride comfort is a high priority, such as active stabilizer bars in automobiles.

[0092] Furthermore, to ensure the stable installation of the output bearing 101, this embodiment has optimized the bearing fixing method. For example... Figure 4 , Figures 9 to 11 As shown, the outer cylinder 11 is provided with a bearing mounting groove. The inner wall of the bearing mounting groove on the side away from the third-stage planetary carrier frame 2031 is provided with an external thread. The outer cylinder 11 is fixed with a fixed outer ring 104 through the external thread. The fixed outer ring 104 fixes the outer ring of the output bearing 101 to the bearing mounting groove. The output sleeve 102 is provided with an annular boss on the side near the third-stage planetary carrier frame 2031. The outer wall of the output sleeve 102 on the side away from the third-stage planetary carrier frame 2031 is provided with an internal thread. The output sleeve 102 is fixed with a fixed inner ring 103 through the internal thread. The fixed inner ring 103 fixes the inner ring of the output bearing 101 between the fixed inner ring 103 and the annular boss.

[0093] In traditional reducer designs, bearings are often axially fixed using elastic retaining rings. This method is prone to loosening or detachment under large axial forces or frequent impact loads, leading to changes in bearing clearance and affecting transmission accuracy. This embodiment employs a threaded connection for fixing. The outer ring 104 is screwed into the bearing mounting groove of the outer cylinder 11 via external threads, applying axial clamping force to the outer ring of the output bearing 101. Similarly, the inner ring 103 is screwed onto the output sleeve 102 via internal threads, and the annular boss locks the inner ring of the output bearing 101 in place. This threaded fixing method is not only convenient to assemble, but more importantly, it provides a much greater axial locking force than a retaining ring, ensuring that the output bearing 101 remains stable during long-term reducer operation, especially under conditions of large axial loads, thus guaranteeing the operational reliability of the output mechanism 100.

[0094] Example 4: This example optimizes the structure of the second / third stage gear ring based on Example 1. For example... Figure 11 As shown, the second / third stage gear ring is integrally formed on the inner side wall of the outer cylinder. The second / third stage gear ring consists of an installation section and a meshing section with different tooth tip circle diameters and the same tooth root circle diameter. The tooth tip between the installation section and the meshing section is smoothly transitioned by a chamfer. The tooth tip circle diameter of the meshing section is smaller than that of the installation section. The meshing section is located on the side closer to the first stage gear ring.

[0095] Specifically, the second / third stage gear rings are integrally formed using a molding process, such as broaching, directly machined onto the inner wall of the outer cylinder 11. This ensures the structural integrity of the second / third stage gear rings and the outer cylinder 11, improving rigidity. In this embodiment, the root circle diameters of the mounting section and the meshing section are the same, meaning that their pitch circle diameters and base circle diameters are identical. This ensures that the basic parameters of gear meshing (such as module and pressure angle) are the same, thereby ensuring that the third-stage planetary gear 2032 can mesh correctly in both areas. The difference between the two lies in the tip circle diameter. The tip circle diameter of the mounting section is larger, meaning its tooth groove opening is wider; the tip circle diameter of the meshing section is smaller, meaning its tooth groove opening is relatively narrower, which is the standard tooth groove width during normal operation.

[0096] The purpose of this variable diameter structure is to improve the ease of assembly of the staggered gear 306. Because the staggered gear 306 has an internal elastic preload 305, there is a preload force between its sub-gears 304 in the free state or during the initial assembly stage, resulting in a misalignment angle on the tooth surface. If it is forcibly installed directly into a standard-sized gear ring, interference, jamming, or even damage to the gear structure can easily occur.

[0097] In this embodiment, during assembly, the staggered gear 306 first enters the mounting section area. Due to the larger tip circle diameter and wider tooth groove entrance in the mounting section, the staggered gear 306 can slide in more easily, greatly reducing the initial assembly resistance. Subsequently, as the assembly progresses, the staggered gear 306 smoothly transitions along the chamfer between the mounting section and the meshing section, gradually being pressed into the meshing section. During this process, the staggered gear 306 is squeezed by the tooth groove sidewall, the elastic preload 305 is further compressed, and the misalignment angle is gradually adjusted to the working state. Finally, the staggered gear 306 fully enters the meshing section and is in the working meshing position. At this time, the tooth surfaces of the slave gear 304 are tightly attached to both sides of the tooth groove of the second / third stage gear ring, achieving backlash-free meshing. This structure not only solves the assembly difficulty problem caused by the preload of the staggered gear 306, but also ensures the backlash elimination effect in the final working state, achieving a balance between assembly convenience and transmission accuracy. It should be understood that the chamfer transition design is to avoid hard collisions between gears at abrupt diameter changes, serving as a guide and buffer.

[0098] Example 5: Figures 16-19 As shown, in this embodiment, a first thrust bearing 20 is provided between the secondary planetary carrier frame 2021 and the tertiary planetary carrier frame 2031, a second washer 301 is provided between the primary planetary carrier frame 2011 and the secondary planetary carrier frame 2021, and a third washer 302 is provided on the inner top wall of the tertiary planetary carrier frame 2031. A first floating disk 14 is provided on the surface of the primary planetary carrier frame 2011 near the secondary planetary carrier frame 2021, and a second floating disk 15 is provided on the surface of the secondary planetary carrier frame 2021 near the primary planetary carrier frame 2011. Both the first floating disk 14 and the second floating disk 15 include a support layer and a flexible layer, both of which are annular and coaxial. The support layer is entirely made of metal, and the flexible layer is entirely made of rubber, with several turbine-shaped blades (also made of rubber) provided on the surface of the flexible layer. The first floating disk 14 is fixedly connected to the primary planetary carrier frame 2011 through its support layer, and the two remain coaxial; the second floating disk 15 is fixedly connected to the secondary planetary carrier frame 2021 through its support layer, and the two remain coaxial.

[0099] The support layer of the first floating disk 14 has an annular groove on the end face near the second floating disk 15, and an opening for the secondary sun gear 2013 to pass through in the middle of the support layer. The support layer of the second floating disk 15 has an annular groove on the end face near the first floating disk 14, and an opening for the secondary sun gear 2013 to pass through in the middle of the support layer. The inner diameter of the annular groove in the middle of the first floating disk 14 and the second floating disk 15 matches the outer diameter of the second washer 301. The second washer 301 is disposed between the first floating disk 14 and the second floating disk 15 through the annular groove in the middle of the support layer of the first floating disk 14 and the second floating disk 15. The depth of the annular groove in the middle of the support layer of the first floating disk 14 and the second floating disk 15 is less than or equal to half the thickness of the second washer 301, so that the bottom plane of the annular groove in the middle of the first floating disk 14 and the second floating disk 15 abuts against the two end faces of the second washer 301, respectively.

[0100] In this embodiment, the depth of the annular groove in the middle of the first floating disk 14 and the second floating disk 15 is one-third of the thickness of the second washer 301, and the total thickness of the turbine blades of the first floating disk 14 and the second floating disk 15 is more than one-third of the thickness of the second washer 301, so that the turbine blades of the first floating disk 14 and the second floating disk 15 remain in contact.

[0101] The first floating disk 14 has several first through holes 18, which penetrate its support layer and flexible layer. Several first recesses 16 are integrally formed at the edge of the surface of the primary planetary carrier 2011, and are evenly distributed circumferentially on the surface of the primary planetary carrier 2011; the first recesses 16 cover the areas where the first through holes 18 are located. The second floating disk 15 has several second through holes 19, which penetrate its support layer and flexible layer. Several second recesses 17 are integrally formed at the edge of the surface of the secondary planetary carrier 2021, and are evenly distributed circumferentially on the surface of the secondary planetary carrier 2021; the second recesses 17 cover the areas where the second through holes 19 are located.

[0102] During the overall operation of the reducer, the first-stage planetary carrier 2011 and the second-stage planetary carrier 2021 rotate. The first floating disk 14 rotates synchronously with the first-stage planetary carrier 2011, and the second floating disk 15 rotates synchronously with the second-stage planetary carrier 2021. The grease / lubricating oil inside the reducer can be evenly dispersed around it by the turbine-shaped blades on the flexible surfaces of the first and second floating disks 14 and 15, promoting the circumferential flow and dispersion of the grease / lubricating oil. Simultaneously, since the reducer decelerates progressively from the first-stage reducer 201 to the third-stage reducer 203, the rotational speed of the first-stage planetary carrier 2011 is greater than that of the second-stage planetary carrier 2021. According to Bernoulli's principle, the first floating disk... The moving disk 14 provides a low-pressure area on the first-stage planetary carrier 2011 side. The grease / lubricating oil tends to flow laterally from the second-stage planetary carrier 2021 side to the first-stage planetary carrier 2011 side. Due to the centrifugal force provided by the first floating disk 14 and the second floating disk 15, the grease / lubricating oil enters the area between the first floating disk 14 and the second floating disk 15 through the second recess 17 and the second through-hole 19, then gradually flows from the first floating disk 14 to the second floating disk 15 side, and flows towards the edge based on centrifugal force, entering the first-stage planetary carrier 2011 area through the first through-hole 18 and the first recess 16, thereby achieving axial flow dispersion of the grease / lubricating oil. The combination of circumferential and axial flow dispersion of the grease / lubricating oil significantly improves the overall cooling and lubrication effect of the reducer.

[0103] When the reducer is applied within the stabilizer bar, the stabilizer bar is arranged horizontally or nearly horizontally on the vehicle chassis. The support layer of the first floating disc 14 and the second floating disc 15 and the second washer 301 provide support and lubrication for the primary planetary carrier skeleton 2011 and the secondary planetary carrier skeleton 2021. In this embodiment, due to the depth design of the annular groove in the middle of the first floating disc 14 and the second floating disc 15, and the total thickness design of the turbine blades of the first floating disc 14 and the second floating disc 15, the turbine blades on the surface of the flexible layer remain in contact. The support layer and the second washer 301 serve as support under complex working conditions, while under normal simple working conditions, the turbine blades on the surface of the flexible layer provide support, thereby reducing the noise and heat generated by the contact between the support layer and the second washer 301 and improving the NVH performance of the vehicle. Furthermore, under normal and simple operating conditions, the turbine-shaped blades on the flexible layer surface can eliminate the gap between the first-stage planetary carrier 2011 and the second-stage planetary carrier 2021, improving the operational stability of both 2011 and 2021. Since the turbine-shaped blades on the flexible layer surface are made of rubber and possess a certain degree of elasticity, after prolonged operation of the reducer, the deformation of the turbine-shaped blades on the flexible layer surface can compensate for the additional gap between the first-stage and second-stage planetary carriers 2011 caused by reducer wear. This ensures that the reducer maintains good stability between the first-stage and second-stage planetary carriers 2011 even after long-term operation, resulting in lower noise levels.

[0104] Example 6: In this example, the size of the first through hole 18 on the first floating disk 14 is smaller than the size of the second through hole 19 on the second floating disk 15, and the number of the first through holes 18 and the second through holes 19 are the same; at the same time, the diameter of the annular groove in the middle of the first floating disk 14 is smaller than the diameter of the annular groove in the middle of the second floating disk 15. This results in a smaller flow space for grease / lubricating oil on the second floating disk 15 side (secondary planetary carrier 2021 side) compared to the first floating disk 14 side (primary planetary carrier 2011 side). When the grease / lubricating oil flows to the primary planetary carrier 2011 side, it flows faster through the first through hole 18 and dispersed from the first recess 16. This promotes axial flow to the primary planetary carrier 2011 side, where it is quickly dispersed to the inner wall of the outer cylinder 11 by the centrifugal force of the primary planetary carrier 2011. It then flows back along the inner wall of the outer cylinder 11 to the secondary planetary carrier 2021 and tertiary planetary carrier 2031 side. This promotes rapid circulation of grease / lubricating oil on the primary planetary carrier 2011 side, meeting the cooling and lubrication needs of the rapid rotation of the primary planetary carrier 2011 and primary planetary gear 2012. Furthermore, the faster the rotational speed of the first-stage planetary carrier 2011 and the first-stage planetary gear 2012, the stronger the tendency of the corresponding grease / lubricating oil to flow from the second floating disk 15 side to the first floating disk 14 side. That is, the flow speed of the grease / lubricating oil can be matched with the overall rotational speed of the reducer, meet the cooling and lubrication requirements of the reducer, and improve the operational reliability and service life of the reducer.

[0105] Example 7: This example, based on the above examples, provides a detailed description of the specific structure and fixing method of the staggered gear 306. For example... Figure 20 and Figure 21 As shown, the staggered gear 306 includes at least two sub-gears 304. Each sub-gear 304 has a limiting part. Each sub-gear 304 is sleeved on a third-stage planetary shaft 21. The third-stage planetary shaft 21 is located in the third-stage planetary cavity. An elastic preload member 305 is provided between adjacent sub-gears 304. The two ends of the elastic preload member 305 contact and abut against the limiting parts of the adjacent sub-gears 304 respectively, providing preload forces in opposite directions to the adjacent sub-gears 304, so that a misalignment angle is formed between the opposing teeth of the adjacent sub-gears 304.

[0106] In this embodiment, two sub-gears 304 are used as an example for explanation. The two sub-gears 304 are coaxially mounted on the third-stage planetary shaft 21. The limiting part can be a limiting block integrally formed on the end face of the sub-gear 304, or it can be a groove structure machined on the sub-gear 304. The elastic preload 305 is preferably a retaining ring with an opening. During assembly, the retaining ring is located between the two sub-gears 304, and its two ends abut against the limiting parts on the two sub-gears 304 respectively, so that the opposing teeth on the two sub-gears 304 maintain a misalignment angle.

[0107] When the staggered gear 306 is engaged with the second / third stage gear ring, the teeth of the two sub-gears 304 will respectively adhere to two opposite sides of the tooth groove of the second / third stage gear ring. One sub-gear 304 is responsible for contact during forward drive, and the other sub-gear 304 is responsible for contact during reverse drive, or both work together to eliminate the intermediate backlash. Eliminating tooth backlash eliminates the need for the reducer to overcome idle travel when switching between forward and reverse directions, significantly improving dynamic response speed and transmission accuracy. It should be understood that the number of sub-gears 304 can be set to three or more according to the backlash elimination accuracy requirements, all of which are within the protection scope of this invention.

[0108] Furthermore, to ensure the stability of the staggered gear 306 under impact loads, this embodiment optimizes the fixing method of the third-stage planetary shaft 21. For example... Figure 20 and Figure 21 As shown, a first fixing hole 22 is provided on the side wall of the third-stage planetary cavity, and a second fixing hole 23 is provided on the side wall of the third-stage planetary shaft 21. An elastic cylindrical pin 24 is interference-fitted in the first fixing hole 22 and the second fixing hole 23, and the elastic cylindrical pin 24 provides radial force to the side walls of the first fixing hole 22 and the second fixing hole 23.

[0109] In traditional planetary reducers, planetary shafts are often axially fixed using snap rings. However, in applications such as automotive active stabilizer bars, reducers frequently face starts and stops and severe impact vibrations, making snap rings prone to detachment or failure. This embodiment uses elastic cylindrical pins 24 for fixing. A first fixing hole 22 penetrates the side wall of the third-stage planetary carrier frame 2031, and a second fixing hole 23 is located at the mounting end of the third-stage planetary shaft 21. During assembly, the elastic cylindrical pin 24 is driven into the hole. Because its outer diameter is slightly larger than the hole diameter, the interference fit generates radial tension. This radial force causes the elastic cylindrical pin 24 to engage with the hole wall, enabling it to withstand extremely high shear and impact forces, ensuring that the third-stage planetary shaft 21 remains stable and does not loosen under harsh operating conditions. This fixing method is simple in structure but extremely reliable.

[0110] Example 8: This example also provides a stabilizer bar, which is an active stabilizer bar, and the stabilizer bar includes the reducer described in any of the above examples.

[0111] Specifically, the active stabilizer bar is a key component in modern automotive chassis suspension systems. It is primarily used to actively apply reverse torque to suppress body roll when the vehicle is cornering or encountering complex road conditions, thereby improving vehicle handling stability and ride comfort. In this embodiment, the reducer, as the core transmission component of the active stabilizer bar actuator, is installed in the vehicle's chassis suspension system. The reducer's input end is connected to the drive motor to receive the high-speed rotational power from the motor; the reducer's output end O2 is connected to the rocker arm via the output sleeve 102, transmitting the reduced and amplified torque to the rocker arm. The rocker arm then generates a torsional motion that acts on the vehicle chassis, causing the vehicle body to depress or lift.

[0112] Based on the technical features of the aforementioned embodiments, the reducer of this embodiment exhibits significant technical advantages when applied to an active stabilizer bar. Firstly, due to the use of a staggered gear 306 structure, the backlash in the final stage of the reducer's transmission is effectively eliminated. During high-speed cornering or bumpy driving, road feedback and vehicle posture change extremely rapidly, requiring a fast stabilizer bar response. Traditional reducers, due to backlash, require the motor to eliminate this backlash before the stabilizer bar can move, resulting in a delayed response. However, the reducer of this embodiment achieves backlash-free meshing through the pre-tightening backlash elimination effect of the staggered gear 306, enabling the motor's output torque to be quickly transmitted to the rocker arm, greatly improving the response speed of the active stabilizer bar, thereby allowing for more precise control of vehicle posture and enhanced driving safety.

[0113] Secondly, the cooperation between the petal-shaped boss 105 and the elastic layer 303 in the output mechanism 100 effectively buffers the impact vibration caused by starting and stopping, as well as the reverse impact transmitted to the reducer from road bumps, during the frequent forward and reverse switching of the stabilizer bar. This not only protects the gear structure inside the reducer and extends its service life, but also significantly reduces transmission noise and improves the overall NVH (noise, vibration, and harshness) performance of the vehicle, meeting the stringent requirements of high-end automobiles for smoothness and quietness.

[0114] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A multi-stage coaxial reducer, characterized in that, Includes an outer cylinder, inside which are provided a first-stage gear ring and a second / third-stage gear ring, and inside which are provided a first-stage reducer, a second-stage reducer and a third-stage reducer arranged coaxially in sequence; The first-stage reducer includes a first-stage planetary carrier frame, which is fixed in an axial position. Several first-stage planetary cavities are reserved inside the first-stage planetary carrier frame. First-stage planetary gears are rotatably connected inside the first-stage planetary cavities, and all first-stage planetary gears mesh with the first-stage ring gear. A second-stage sun gear is coaxially fixedly connected to the first-stage planetary carrier frame. The secondary reducer includes a secondary planetary carrier frame, which floats axially. Several secondary planetary cavities are reserved inside the secondary planetary carrier frame. Secondary planetary gears are rotatably connected inside the secondary planetary cavities, and all secondary planetary gears mesh with the secondary sun gear and the second / third stage gear ring. The secondary planetary carrier skeleton is coaxially and fixedly connected to the third-stage sun gear; The three-stage reducer includes a three-stage planetary carrier frame, which floats axially. The three-stage planetary carrier frame has several reserved three-stage planetary cavities. Three-stage planetary gears are rotatably connected in the three-stage planetary cavities. All three-stage planetary gears mesh with the three-stage sun gear and the second / third-stage ring gear. The three-stage planetary carrier frame is connected to an output mechanism. The second / third stage gear ring consists of an installation section and a meshing section with different tip circle diameters and the same root circle diameter. The tip of the tooth between the installation section and the meshing section is smoothly transitioned by a chamfer. The tip circle diameter of the meshing section is smaller than that of the installation section. The meshing section is located on the side closer to the first stage gear ring. At least one of the three-stage planetary gears is a staggered gear; the staggered gear includes at least two sub-gears, each sub-gear having a limiting portion, and each sub-gear is fitted onto a three-stage planetary shaft, which is located in the three-stage planetary cavity. An elastic preload is provided between adjacent sub-gears, with both ends of the elastic preload contacting and abutting against the limiting portions of the adjacent sub-gears, providing preload forces in opposite directions to the adjacent sub-gears, thereby creating a misalignment angle between the opposing teeth of the adjacent sub-gears.

2. The multi-stage coaxial reducer according to claim 1, characterized in that, A first washer is provided between the secondary planetary carrier frame and the tertiary planetary carrier frame, and the first washer between the two is in contact with or abuts against the secondary planetary carrier frame; a second washer is provided between the primary planetary carrier frame and the secondary planetary carrier frame, and the second washer between the two is in contact with or abuts against the primary planetary carrier frame; the first washer, the second washer, the secondary sun gear, and the tertiary sun gear are coaxial.

3. The multi-stage coaxial reducer according to claim 1, characterized in that, A first thrust bearing is provided between the secondary planetary carrier and the tertiary planetary carrier, and the first thrust bearing between them contacts and abuts against the secondary or tertiary planetary carrier; a second thrust bearing is provided between the primary and secondary planetary carriers, and the second thrust bearing between them contacts and abuts against the primary or secondary planetary carrier; the first thrust bearing, the second thrust bearing, the secondary sun gear, and the tertiary sun gear are coaxial.

4. The multi-stage coaxial reducer according to claim 1, characterized in that, A third washer is provided on the inner top wall of the third-stage planetary carrier frame. A T-shaped washer is coaxially inserted into the third-stage sun gear. The T-shaped washer is made of elastic material and extends to the outside of the third-stage sun gear, covering the end face of the third-stage sun gear. The T-shaped washer is located between the third washer and the end face of the third-stage sun gear.

5. The multi-stage coaxial reducer according to claim 1, characterized in that, The output mechanism includes a petal-shaped boss fixedly connected to the three-stage planetary carrier skeleton. An output bearing is provided inside the outer cylinder. An output sleeve is rotatably connected inside the outer cylinder through the output bearing. A petal-shaped groove is provided inside the output sleeve. The petal-shaped boss is inserted into the petal-shaped groove. An elastic layer is provided between the petal-shaped boss and the petal-shaped groove. The output sleeve is used to connect the output end.

6. The multi-stage coaxial reducer according to claim 5, characterized in that, The outer cylinder is provided with a bearing mounting groove. The inner wall of the bearing mounting groove on the side away from the third-stage planetary carrier skeleton is provided with an external thread. A fixed outer ring is fixedly connected to the outer cylinder through the external thread. The fixed outer ring fixes the outer ring of the output bearing to the bearing mounting groove. The output sleeve is provided with an annular boss on the side near the third-stage planetary carrier skeleton. The outer wall of the output sleeve on the side away from the third-stage planetary carrier skeleton is provided with an internal thread. A fixed inner ring is fixedly connected to the outside of the output sleeve through the internal thread. The fixed inner ring fixes the inner ring of the output bearing between the fixed inner ring and the annular boss.

7. The multi-stage coaxial reducer according to claim 1, characterized in that, The primary gear ring is press-fitted or welded to the inner wall of the outer cylinder, and the secondary / tertiary gear rings are integrally formed on the inner wall of the outer cylinder.

8. The multi-stage coaxial reducer according to claim 1, characterized in that, The first-stage planetary carrier skeleton has a first-stage protrusion at one end near the second-stage planetary carrier skeleton, and the second-stage sun gear is fixedly connected to the first-stage protrusion. The second-stage planetary carrier skeleton has a second-stage protrusion at one end near the third-stage planetary carrier skeleton, and the third-stage sun gear is fixedly connected to the end face of the second-stage protrusion. The second-stage sun gear does not contact the second-stage protrusion.

9. The multi-stage coaxial reducer according to claim 1, characterized in that, The third-stage planetary cavity has a first fixing hole on its sidewall, and the third-stage planetary shaft has a second fixing hole on its sidewall. The first fixing hole and the second fixing hole are fitted with elastic cylindrical pins, which provide radial force to the sidewalls of the first fixing hole and the second fixing hole.

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